Process for producing photoresist composition, filter, coater and photoresist composition

ABSTRACT

A technique to acquire a photoresist composition which can reduce occurrence of defects of a resist pattern after development is provided. Further, a technique to obtain a photoresist composition having excellent storage stability characteristics as a resist solution (storage stability); and a technique to obtain a photoresist composition which reduces the change of sensitivity and resist pattern size after treatment almost completely are provided. A photoresist composition containing a resin component (A), an acid-generating component (B) for generating an acid under exposure, and an organic solvent (C) is passed through a first filter  2   a  equipped with a first membrane having zeta potential of more than −20 mV but no more than 15 mV in distilled water of pH 7.0.

TECHNICAL FIELD

The present invention relates to a method for manufacturing aphotoresist composition, a filtering device, a coating device and aphotoresist composition.

The disclosures of the following applications are herein incorporated:Japanese Patent Application No. 2002-368931 and Japanese PatentApplication No. 2003-416583.

BACKGROUND ART

For example, as described in Japanese Unexamined Patent Application,First Publication No. 2002-296779 (patent reference 1), a chemicallyamplified photoresist composition obtained by using a KrF excimer laser,an ArF excimer laser, an F₂ excimer laser, an EUV (extreme UV ray) or anEB (electron beam) or the like for a light source (radiation source)typically contains a resin component (A), an acid-generating component(B) for generating an acid under exposure and an organic solvent (C)capable of dissolving these components.

A resist pattern having high resolution, high sensitivity and anexcellent shape or the like is required of the chemically amplifiedphotoresist composition.

A resist pattern having high resolution of 0.15 μm or lower has recentlybeen demanded, and the reduction of the defects (surface defects) of theresist pattern after development over that of a conventional resistpattern has been further demanded in addition to the characteristics.

The defect typically is an actual nonconformity defection when theresist pattern after development is observed from directly above by asurface defect observation apparatus (trade name “KLA”) manufactured by,for example, KLA Tencor Company. This nonconformity is, for example,scum, bubbles, waste or a bridge between resist patterns or the likeafter development.

So as to reduce the defects, improvements in the resist composition suchas a resin component of the resist composition, an acid-generatingcomponent and a solvent component have been mainly attempted [JapaneseUnexamined Patent Application, First Publication No. 2001-56556 (patentreference 2)).

While a resist solution (a photoresist composition of a solution state)is stored, a storage stability characteristic as a resist solution(while the photoresist composition is stored, solid foreign matter isgenerated in the photoresist composition; storage stability) in whichminute particles are generated also poses a problem, and the improvementthereof is desired.

For the improvement of the storage stability characteristic as a resistsolution, the improvement of the resist composition has been attemptedin the same manner as the above case [Japanese Published UnexaminedPatent Application No. 2001-22072 (patent reference 3)].

[Patent reference 1] Japanese Unexamined Patent Application, FirstPublication No. 2002-296779

[Patent reference 2] Japanese Unexamined Patent Application, FirstPublication No. 2001-56556

[Patent reference 3] Japanese Unexamined Patent Application, FirstPublication No. 2001-22072

[Patent reference 4] Japanese Unexamined Patent Application, FirstPublication No. 2002-62667

[Patent reference 5] Japanese Unexamined Patent Application, FirstPublication No. 2001-350266

DISCLOSURE OF THE INVENTION

However, the techniques described in patent references 2 and 3 have notattained a sufficient effect yet.

The generation of the above minute particulates may cause the abovedefects, and the improvement of the storage stability characteristic asa resist solution is strongly desired for the reduction of the defects.

However, up until now, methods for sufficiently improving the defectsand storage stability of the resist pattern after development have notbeen known.

A method for manufacturing the photoresist composition obtained byreducing the amount of the particulates in the photoresist compositioncirculated through a line by passing the photoresist composition througha filter is proposed in Japanese Unexamined Patent Application, FirstPublication No. 2002-62667 (patent reference 4).

As shown in patent reference 4, a method for manufacturing thephotoresist composition by the manufacture of the photoresistcomposition and passing the photoresist composition through the filterhas been known. However, the method has not sufficiently reduced theabove defects of the resist pattern after development and improved thestorage stability.

A method for manufacturing a photoresist composition by passing aphotoresist composition through a filter having positive zeta potentialhas been proposed in Japanese Published Unexamined Patent ApplicationNo. 2001-350266 (patent reference 5). However, according toinvestigation by the inventors, the treatment of the photoresistcomposition yielded by the method described in patent reference 5 maycause alteration of the composition. The alteration of the compositionhas a disadvantage since the alteration of the composition causesalteration of sensitivity of the photoresist composition or alterationof the resist pattern size.

In addition, of the various types of resist pattern defects that existfollowing developing, resolving the defect problems that appear duringthe formation of very fine resist patterns with pattern sizes of no morethan 130 nm or which are produced using ArF excimer lasers onwards asthe light source, namely, ArF excimer lasers, F₂ excimer lasers, EUV,and EB and the like, is now becoming critical.

That is, it has been a very big problem to reduce defects such as minutescum and microbridges after development, which did not cause a largeproblem in the resist for the KrF excimer laser. However, the problemshave not been solved by the above prior art.

The present invention has been accomplished in view of the foregoing. Itis an object of the present invention to provide a technique to obtain aphotoresist composition which can reduce occurrence of defects in theresist pattern after development, particularly the occurrence of minutescum and microbridges.

It is another object of the present invention to provide a technique toobtain a photoresist composition having an excellent storage stabilitycharacteristic as a resist solution (storage stability).

It is another object of the present invention to provide a technique toobtain a photoresist composition which prevents the alteration ofsensitivity and resist pattern size after treatment almost completely.

To attain the above object, the present invention applies the followingconstitutions.

According to a first aspect of the present invention, there is provideda method for manufacturing a photoresist composition comprising the stepof passing a photoresist composition containing a resin component (A),an acid-generating component (B) for generating an acid under exposureand an organic solvent (C) through a first filter equipped with a firstmembrane having zeta potential of more than −20 mV but no more than 15mV in distilled water of pH 7.0.

According to a second aspect of the present invention, there is provideda method for manufacturing a photoresist composition comprising the stepof passing a photoresist composition containing a resin component (A),an acid-generating component (B) for generating an acid under exposureand an organic solvent (C) through a first filter equipped with a firstmembrane having a critical surface tension of 70 dyne/cm or more.

According to a third aspect of the present invention, there is provideda filtering device comprising:

a storing part for storing a photoresist composition containing a resincomponent (A), an acid-generating component (B) for generating an acidunder exposure, and an organic solvent (C); and

a first filtering part for passing the photoresist composition through,

wherein the first filtering part has a first filter equipped with afirst membrane having zeta potential of more than −20 mV but no morethan 15 mV in distilled water of pH 7.0.

According to a fourth aspect of the present invention, there is provideda filtering device comprising:

a storing part for storing a photoresist composition containing a resincomponent (A), an acid-generating component (B) for generating an acidunder exposure, and an organic solvent (C); and

a first filtering part for passing the photoresist composition through,

wherein the first filtering part has a first filter equipped with afirst membrane having a critical surface tension of 70 dyne/cm or more.

According to a fifth aspect of the present invention, there is provideda coating device for a photoresist composition equipped with thefiltering device according to the third or fourth aspect of the presentinvention.

According to a sixth aspect of the present invention, there is provideda photoresist composition obtained by the method for manufacturingaccording to the first or second aspect of the present invention.

According to a seventh aspect of the present invention, there isprovided a method for manufacturing a photoresist composition comprisingthe step of passing a photoresist composition containing a resincomponent (A), an acid-generating component (B) for generating an acidunder exposure, and an organic solvent (C) through a first filterequipped with a first membrane having a pore diameter of 0.04 μm or lessand made of a NYLON membrane.

According to an eighth aspect of the present invention, there isprovided a filtering device comprising:

a storing part for storing a photoresist composition containing a resincomponent (A), an acid-generating component (B) for generating an acidunder exposure, and an organic solvent (C); and

a first filtering part for passing the photoresist composition through,

wherein the first filtering part has a first filter equipped with afirst membrane made of a NYLON membrane of 0.04 μm or less.

According to a ninth aspect of the present invention, there is provideda coating device for a photoresist composition equipped with thefiltering device according to the eighth aspect of the presentinvention.

The defects appear on the resist pattern persistently, and are differentfrom so-called pinhole defects in the resist coating film before patternformation.

Herein, “(meta)acryllate” means at least one of acrylate andmethacrylate. “Construction unit” means a unit derived from a monomerconstituting the polymer.

The present invention can provide a technique to obtain the photoresistcomposition which can reduce the occurrence of defects of the resistpattern after development, particularly the occurrence of minute scumand microbridges.

Also, the present invention can provide a technique to obtain aphotoresist composition having an excellent storage stabilitycharacteristic as a resist solution (storage stability).

Also, the present invention can provide a technique to obtain aphotoresist composition which prevents variation of the sensitivity andresist pattern size after treatment almost completely.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic constitution diagram showing an example of afiltering device of the present invention.

FIG. 2 is a schematic constitution diagram showing an example of acoating device equipped with the filtering device of the presentinvention.

FIG. 3 is a graph of a Zisman Plot.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

[The Procedure and Device of Operation]

Hereinafter, one example of the method for manufacturing the photoresistcomposition and filtering device of the present invention will bedescribed according to the procedure.

First, a filtering device is prepared, which is provided with a firstfiltering part equipped with a first filter having a first membrane(filtering membrane) having zeta potential of more than −20 mV but nomore than 15 mV in distilled water of pH 7.0, and a second filteringpart equipped with a second filter having a second membrane (filteringmembrane) made of polyethylene or polypropylene.

The zeta potential is the electric potential of diffused ion layersaround charged particles in a liquid.

In more detail, when ultrafine powder has electric charge in the liquid,so as to eliminate the electric charge, ions having reverse electriccharge are drawn to the fine powder by electrostatic force, and therebyelectric double layers are formed. The potential of the surface of theoutermost of the double layers is the zeta potential.

It is said that measurement of the zeta potential is effective fordetermining the surface structure of the fine powder and fine particles.The term “zeta potential” used hereinafter means “zeta potential indistilled water of pH 7.0.” The numerical value in the present inventionis a nominal value given by a manufacturer of the filter.

The first embodiment uses a filter equipped with a membrane having thezeta potential of a specific range of the nominal value given by themanufacturer of the filter.

By using a membrane having specific zeta potential, defects,particularly minute scum and microbridges can be effectively reduced,and the storage stability as a resist solution can be effectivelyimproved.

In the present invention, for example, the filter may be equipped with amembrane for passing at least the photoresist composition through, and asupporting member for supporting the membrane. Filters having variousmaterials and various pore diameters are manufactured and sold asfilters for filtering ultrapure water, high-purity chemical liquids andfine chemicals or the like by filter manufacturers such as Japan PallCorporation, Advantec Toyo Corporation, Mykrolis Corporation and KitzCorporation.

In the present invention, the photoresist composition passed through thefilter may be a photoresist composition having the same concentration asthat of manufactured products, or may be a so-called undiluted solutionhaving a solid content concentration of about 8 to about 15% by massbefore dilution.

The term “filtration” used in the present invention contains typicallyused chemical “filtration” (“only the phase [gas or liquid] of a fluidwhich is penetrated by using a membrane and phase of “porous substance,and half-solid phase or solid is separated from the phase of the fluid,”Encyclopaedia Chimica 9 Jul. 31, 1962 publication, Kyoritsu Shuppan Co.,Ltd.). In addition, the term “filtration” contains the case of merely“passing through a filter,” that is, the case that the half-solid phaseor solid trapped by the membrane when passing through the membranecannot be visually confirmed or the like.

The photoresist composition containing the resin component (A), theacid-generating component (B) for generating the acid under exposure,and the organic solvent (C) are conventionally prepared.

Then, as shown in FIG. 1, when the photoresist composition is suppliedto a first filtering part 2 from a storage tank 1 (the storing part forthe photoresist composition), the photoresist composition is passedthrough a first membrane in a first filter 2 a provided in the firstfiltering part 2 and is filtered. The filtrate is supplied to a firstfiltrate storage tank 3. When the filtrate (photoresist composition) isthen supplied to a second filtering part 4 from the first filtratestorage tank 3, the filtrate is passed through a second membrane in asecond filter 4 a provided in the second filtering part 4 and isfiltered.

Finally, the filtrate [photoresist composition] is put into a container5 as a manufactured product.

Herein, although the second filtering part 4 (the second filter 4 a) isnot indispensable, the burden of filtration on the first filter 2 a ofthe first filtering part 2 can be reduced by using the second filter 4.In addition, it is preferable in that the effect of defect reduction andthe storage stability characteristic as a resist solution also improve.

The membrane of the second filter 4 a is not particularly limited aslong as the membrane is conventionally used for the filtrationapplication or the like of the photoresist composition. Examples of themembrane include a fluororesin such as PTFE (polytetrafluoroethylene); apolyolefin resin such as polypropylene or polyethylene; and a polyamideresin such as NYLON 6 (registered trademark) and NYLON 66 (registeredtrademark).

Of these, when one membrane selected from the membranes made ofpolyethylene and polypropylene is combined with the first filter, boththe defect reduction effect and the storage stability characteristic asa resist solution are preferable as compared with that of the othermembranes. The membrane made of polypropylene contains a high-densitypolypropylene (HDPE) membrane and an ultrahigh molecular weightpolypropylene (UPE) in addition to normal polypropylene.

In the specific procedure for performing the filtration using the secondfilter 4 a after the step of filtering by using the first filter 2 aequipped with the first membrane of the present invention, thephotoresist composition is first filtered by the first filter 2 aequipped in the first filtering part 2 of the present invention. Thephotoresist composition is then supplied to the second filtering part 4,and for example, the second filtration is performed by using the secondfilter 4 a equipped with the membrane made of polyethylene orpolypropylene. The photoresist composition is finally filtered by afilter equipped with the membrane made of PTFE. In this case, it is notnecessary to perform filtration by the last filter equipped with themembrane made of PTFE. However, it is preferable to perform thefiltration.

The step of pre-filtration for filtering once or twice using the samefilter as the second filter 4 a may also be provided before the step offiltering using the first filter 2 a. The filter used at the step ofpre-filtration is the same as the membrane of the above second filter 4a, and the membrane is preferably selected from membranes made ofpolypropylene and polyethylene.

In a specific procedure for combining the pre-filtration using thesecond filter 4 a with the step for passing the composition through thefirst filter 2 a equipped with the first membrane, for example, thefiltration is first performed by a filter equipped with a membrane madeof PTFE. A second filtration is then performed by the second filter 4 aequipped with the membrane made of polypropylene or polyethylene. Thephotoresist composition is then supplied to the first filtering part 2,and is filtered by the first filter 2 a provided in the first filteringpart 2. Although it is not necessary to perform the filtration by thefirst filter equipped with the membrane made of the PTFE in this case,it is preferable to perform the filtration.

An operation for performing the filtration using the second filter 4 amay be combined both before and after filtration of the first filter 2 aprovided in the first filtering part 2 in the present invention.

If the resist composition is filtered by the first filter 2 a at leastonce in the present invention, an excellent effect is obtained in viewof the defect reduction effect and the storage stability characteristicas a resist solution. The combination or the like of the number of times(number of times of filtration) for passing through the membrane and thefilter equipped with the other kinds of the membranes is notparticularly limited, and can be suitably adjusted for any purpose.

Particularly, filtration by passing the composition through the firstfilter 2 a is performed once or twice, and filtration by passing thecomposition through the second filter 4 a is finally performed. Thereby,the method excels in both the defect reduction effect and the storagestability characteristic as a resist solution. When the filtration usingthe first filter 2 a is performed twice or more, filtrate is passedthrough the first filtering part 2 once by the conventional method, andthe thereby filtered filtrate may be supplied to the first filteringpart 2 again.

The filtering device can be suitably selected by the combination of thefilters in the filtration step, and can be constituted in various formsby providing a tank for storing the photoresist composition before andafter filtration such as the storing part suitably before and after onekind or two kinds or more of filters (filtering parts).

Various forms can be employed for the filtering device of the presentinvention.

For example, the filtering device may be a device used for the abovemanufacturing process of the photoresist composition, or may be a devicemounted on a coating device such as a spinner or a coater-developer.That is, the coating device of the present invention represents acomprehensive concept containing not only a so-called coating device forthe photoresist composition but also a coating device united with otherdevices such as a developer. These coating devices have a nozzle, andthe photoresist composition is usually supplied on a wafer (substrate)from the nozzle to coat the photoresist composition onto the wafer.

Therefore, before the photoresist composition is supplied onto the waferfrom the nozzle, the filtering device of the present invention may beincorporated in the above coating device or the like so that thephotoresist composition is passed through the membrane of the filteringdevice of the present invention. Therefore, before the photoresistcomposition is supplied on the wafer, the cause of the defects in thephotoresist composition is removed, and the defects, particularly minutescum and microbridges can be effectively reduced.

The specific example of the coating device equipped with the filteringdevice of the third, fourth or eighth aspect of the present inventionwhich is the fifth or ninth aspect of the present invention will bedescribed in Example 4-1 and Comparative Example 4-1 described below.

The membrane used for the first filter 2 a has zeta potential of morethan −20 mV but no more than 15 mV; preferably more than −20 mV but nomore than 10 mV; more preferably more than −20 mV but no more than 10mV; and particularly preferably negative zeta potential (provided thatit is less than −20 mV). The membrane is preferable because it isexcellent in the defect reduction effect, particularly of minute scumand microbridges, and in the storage stability characteristic as aresist solution.

The negative zeta potential is −5 mV or less (provided that it is largerthan −20 mV), preferably −10 to −18 mV, and more preferably −12 to −16mV. The membrane of the first filter is particularly preferably made ofNYLON (polyamide), and particularly the filter has a membrane satisfyingthe preferable numerical value range of the negative zeta potential andis made of NYLON.

A filter equipped with a membrane (for example, NYLON 6 (registeredtrademark) or NYLON 66 (registered trademark) or the like) denatured bycharge modification and made from polyamide is common as a filterequipped with a membrane showing positive zeta potential among themembranes having the specific zeta potential used for the first filter 2a.

Examples of filters equipped with membranes showing negative zetapotential include ULTIPORE N66 (product name, manufactured by Japan PallCorporation, zeta potential of about −12 to −16 mV) which is notdenatured by charge modification and is made of NYLON 66 (registeredtrademark); and ULTIPLEAT (registered trademark) P-NYLON Filter (productname, manufactured by Japan Pall Corporation, zeta potential of about−12 to −16 mV, pore diameter of 0.04 μm) made of NYLON 66 (registeredtrademark). Of these, the latter ULTIPLEAT (registered trademark) ismore preferable.

The filter equipped with the membrane showing the negative zetapotential is suitable for the method for manufacturing the photoresistcomposition which is the first, second or seventh aspect of the presentinvention, and the filtering device of the third, fourth or eighthaspect of the present invention.

Examples of the filter used in the coating device equipped with thefiltering device of the third, fourth or eighth aspect of the presentinvention which is the fifth or ninth aspect of the present inventioninclude a P-NYLON FILTER (product name, manufactured by Japan PallCorporation, zeta potential of about −12 to −16 mV, pore diameter of0.04 μm) equipped with a membrane in which the removable form is changedfor the coating device and which is made of NYLON 66 (registeredtrademark). In the removable form of the coating device, only the filteris preferably removed and replaced in the coating device equipped withthe filtering device.

In the present invention, the filter with the membrane having thenegative zeta potential is preferable which is excellent in the defectreduction effect, particularly of minute scum and microbridges, and thestorage stability characteristic as a resist solution. Although thereason is not clear, the present inventors speculate that the filterwith the membrane having the specific zeta potential improves theselective filtration efficacy with respect to a resin having highcontent of the specific particles which affect the defects and thestorage stability as a resist solution, particularly, units having apolar group such as a lactone group or a hydroxyl group such asconstruction units (a2) and (a3) described below. The use of themembrane having negative zeta potential is preferable, because itprovides a photoresist composition in which the sensitivity and the sizeof the resist pattern after being filtrated are substantially unchangedeven if the photoresist composition itself is filtrated. The presentinventors speculate that the reason is because the composition issubstantially unchanged, and for example, a quencher such as anitrogen-containing organic compound or an organic acid is substantiallyunadsorbed.

The pore diameter of the membrane used for the first filter 2 a is thenominal value given by the manufacturer of the filter. The combination(the combination of the form of the filter, a kind of membrane and thenumber of times for passing through the membrane or the like) of thefiltering part is suitably adjusted in view of the productivity and theeffect of the present invention.

For example, when only the first filter 2 a is used without using thesecond filter 4 a, a product in which the pore diameter of the membraneof the first filter 2 a is 0.2 μm or less, preferably 0.1 μm or less,and more preferably 0.04 μm or less is preferably used in view of theeffect. However, if the pore diameter becomes too small, theproductivity (the throughput of the manufacture of the resistcomposition and coating) tends to be reduced. Although the lower limitis about 0.01 μm, the pore diameter is most practically set to 0.02 μmor more.

When the photoresist composition is filtered by combining the firstfilter with the second filter 4 a, a product of 0.1 μm or less, morepreferably 0.04 μm or less is preferably used as the second filter 4 ain the same way in view of the effect. Although the lower limit is about0.01 μm, the pore diameter is practically set to 0.02 μm or more.

In each case, it is preferable that the pore diameter of the membraneused for the first filter 2 a satisfies the range of 0.01 to 0.04 μm,preferably 0.02 to 0.04 μm in view of the defect reduction effect, theeffect of improvement in the storage stability characteristic as aresist solution, and the productivity. The pore diameter is preferably0.04 μm in view of the compatibility of the effect and productivity.

The pore diameter of the membrane of the second filter 4 a is 0.2 μm orless, more preferably 0.1 μm or less, and more preferably 0.02 μm orless. Although the lower limit is not particularly limited, the porediameter is most practically 0.02 μm or more.

It is preferable that the pore diameter of the membrane used for thesecond filter 4 a satisfies the range of 0.02 to 0.1 μm in view of thedefect reduction effect, and the effect of improvement in the storagestability characteristic as a resist solution.

The pore diameter of the second filter herein is the nominal value ofthe manufacturer of the filter in the same way.

A so-called disk type or a cartridge type or the like are typically usedas the shape (form) of the first filter 2 a and second filter 4 a.

It is preferable that the surface area (filtration area) of the firstfilter 2 a and second filter 4 a is suitably adjusted according to thethroughput or the like of the photoresist composition, and the surfacearea is not particularly limited. For example, the surface area may beadjusted in the same way as usual.

The filtration pressures [withstanding differential pressure] of thefirst filter 2 a and second filter 4 a are not particularly limited. Forexample, the filtration pressure is set to the same condition as usual.

The flow velocity of the photoresist composition supplied to the firstfiltering part 2 and the second filtering part 4 is suitably adjusted bythe characteristic and surface area or the like of the filter, and forexample, is set to the same condition as usual.

In the first embodiment, by using the membrane having the specific zetapotential, defects, particularly minute scum and microbridges can beeffectively reduced, and the storage stability as a resist solution canbe effectively improved. If the membrane having negative zeta potentialis particularly used, a photoresist composition in which the sensitivityand the size of the resist pattern are substantially unchanged is alsoeffectively obtained.

The scum and defects of the resist pattern can be estimated as theso-called number of surface defects by a surface defect observationapparatus KLA2132 (product name) manufactured by, for example, KLATencor Company. The microbridges can be confirmed by observing using ameasuring SEM or the like.

The storage stability as a resist solution can be evaluated by measuringthe amount of foreign matter by using a particle counter.

For example, the storage stability characteristic as a resist solutionof the photoresist composition after storing at 40° C. or at roomtemperature after manufacture is evaluated by using a liquid particlecounter (manufactured by Rion Company, product name: particle sensorKS-41 and KL-20K). The device counts the number of particles having aparticle diameter of 0.15 to 0.3 μm or more per 1 cm³. The measuringlimit is usually 20000 pieces/cm³ or more.

The amount of foreign matter in the photoresist composition immediatelyafter manufacture is usually about 10 to 30 pieces/cm³ or less in termsof particles of 0.3 μm or more, and is about 900 pieces/cm³ or less interms of particles of 0.15 μm or more. A characteristic in which thestorage stability characteristic as a resist solution is almostunchanged as compared with that immediately after manufacture,preferably after a half year is obtained by applying the presentinvention.

Whether the composition is changed or not can be evaluated by analyzingand comparing the concentration of the material contained in thephotoresist composition before and after the step for passing throughthe filter, and by measuring the sensitivity (the optimal lightexposure) and the variation of the size of the resist pattern at thetime of forming the resist pattern using the photoresist composition.

Second Embodiment

[The Procedure and Device of Operation]

The second embodiment provides a method for manufacturing a photoresistcomposition comprising the step of passing a photoresist compositioncontaining a resin component (A), an acid-generating component (B) forgenerating an acid under exposure, and an organic solvent (C) through afirst filter equipped with a first membrane having a critical surfacetension of 70 dyne/cm or more. In addition, the second embodimentprovides a filtering device comprising: a storing part for storing aphotoresist composition containing a resin component (A), anacid-generating component (B) for generating an acid under exposure, andan organic solvent (C); and a first filtering part for passing thephotoresist composition through, wherein the first filtering part has afirst filter equipped with a first membrane having a critical surfacetension of 70 dyne/cm or more.

The second embodiment is different from the first embodiment in that thefirst filtering part 2 shown in FIG. 1 is equipped with the first filter2 a having the first membrane satisfying the characteristic of thecritical surface tension of 70 dyne/cm or more.

The critical surface tension is a physical property known as“wettability” of the surface physical property of a polymer, and is asolid surface tension (γc). Since γc cannot be directly evaluated in thesame manner as in liquid, γc is obtained from the formula of Young-Dupreand a Zisman Plot as follows.

The formula of Young-Dupre:γLV cos θ=γSV−γSLWherein θ: contact angle, S: solid, L: liquid, and V: saturated vapor.

When water is used as the liquid, θ is 90°. When θ is 90° or more, thesurface has hydrophobicity, and when θ is near 0°, the surface hashydrophilicity.

Zisman Plot (see FIG. 3):

The contact angle θ is measured by using various liquids having surfacetension γLV, and γLV and cos θ are plotted. If γLV approaches γSV of thesolid surface, θ becomes small, and the contact angle θ becomes 0° at avalue of γLV. The γLV of the liquid when θ becomes 0° is defined as thesurface tension of the solid, that is, the critical surface tension(γc).

γc in the membrane (membrane processed for the filter) (Medium) used forthe filter, and a polymer material (Material) before being used for thefilter (before being processed for the filter) is as follows.

-   Example of a membrane (Medium) with which the filter is equipped and    which is made of NYLON 66: 77 dyne/cm (the unit is omitted below)-   General NYLON 66 (Material) with which the filter is not equipped:    46-   Example of a membrane (Medium) with which the filter is equipped and    which is made of polyethylene or polypropylene: 36-   Example of a membrane (Medium) with which the filter is equipped and    which is made of polytetrafluoroethylene (PTFE): 28-   General PTFE (Material) with which the filter is not equipped: 18.5,    etc.

Thus, γc of the membrane (Medium) with which the filter is processed soas to function as the filter is equipped is different from that of thepolymer material (Material).

γc in the second embodiment means that the critical surface tension ofthe first membrane with which the first filter 2 a is equipped is 70dyne/cm or more, and is not the value of the polymer material(Material). This difference is produced by processing the polymermaterial (Material) so as to be equipped in the filter. Since differentprocessing methods cause different values of critical surface tension inthe same material, it is preferable that the nominal value of thecritical surface tension of the membrane of the filter is respectivelyconfirmed or the measured value is obtained.

The reduction of defects, particularly minute scum and microbridges, andthe effect of the improvement of the storage stability as a resistsolution are acquired by using a filter equipped with a membrane havinga critical surface tension of 70 dyne/cm or more. Since the defectreduction effect becomes inferior otherwise, the upper limit is 95dyne/cm or less. A more preferable range is 75 dyne/cm or more and 90dyne/cm or less, and further preferable range is 75 dyne/cm or more and80 dyne/cm or less.

Although the value of the critical surface tension in the presentinvention is the nominal value of the manufacturer of the filter, thevalues can be easily obtained by dropping multiple liquids having knownsurface tensions onto the targeted membrane, and discerning the boundaryof one liquid soaking into the membrane by its own weight and the otherliquid not soaking.

Examples of filters satisfying the value of the critical surface tensionin the present invention include the above ULTIPLEAT (registeredtrademark) P-NYLON FILTER (product name: manufactured by Japan PallCorporation, zeta potential about −12 to −16 mV, pore diameter of 0.04μm, 77 dyne/cm) made of NYLON 66 (registered trademark).

On the other hand, examples of filters which do not satisfy the value ofthe critical surface tension in the present invention include a filterequipped with a membrane composed by available commercial fluororesinsuch as PTFE, or a polyolefin resin such as polypropylene orpolyethylene.

The value of the critical surface tension of the membrane in thesefilters is about 50 dyne/cm or less as described above.

In the second embodiment, membranes which satisfy the value of the abovecritical surface tension and are not denatured by charge modificationare preferable. “charge modification” has the same meaning as theexpression of “compulsive potential modification” which is not subjectedto charge modification has the same specific zeta potential as the firstfilter 2 a in the first embodiment. It is preferable that use of amembrane having zeta potential of more than −20 mV but no more than 15mV; preferably more than −20 mV but no more than 10 mV; more preferablymore than −20 mV but less than 10 mV; partucularly preferably havingnegative zeta potential (more than −20 mV) can provide a photoresistcomposition in which the sensitivity and size of the resist patternafter being filtrated are substantially unchanged even if thephotoresist composition itself is filtrated. The negative zeta potentialis −5 mV or less (more than −20 mV), preferably −10 to −18 mV, morepreferably −12 to −16 mV.

The preferable embodiment of the pore diameter of the membrane is thesame as that of the first embodiment. Particularly, products arepreferably used, in which the pore diameter of the membrane of the firstfilter 2 a is 0.04 μm or less. However, if the pore diameter is toosmall, the productivity (the manufacture of resist composition and thethroughput of coating) tends to be reduced. Although the lower limit isabout 0.01 μm, the lower limit is most practically 0.02 μm or more.

In the second embodiment, the effects of reduction of defects,particularly minute scum and microbridges, and improvement of thestorage stability as a resist solution can be acquired by using a filterequipped with a membrane having a critical surface tension of 70 dyne/cmor more.

Particularly, even if the photoresist composition itself is filtered byusing the membrane having the above zeta potential, it is preferablethat a photoresist composition is acquired, in which the composition issubstantially unchanged after being processed and change of thesensitivity or size of resist pattern is not substantially caused.

Although the reason is not clear, since the surface of the membrane iswetted easily with the resist composition when the critical surfacetension is 70 dyne/cm or more, the present inventors speculate that theselective filtration efficacy is improved with respect to the specificparticles affecting the defects and reduction of the storage stabilityas a resist solution, particularly, the resin with high content of aunit having a polar group such as a lactone group or a hydroxyl groupsuch as construction units (a2) and (a3) described below.

The present inventors speculate that the alterlation of the electriccharge is decreased and the absorption of the specific substance intothe surface of the membrane is reduced since the membrane has the abovezeta potential, and as a result, composition change of the photoresistcomposition can be reduced.

Third Embodiment

[The Procedure of Operation and Device]

The third embodiment provides a method for manufacturing a photoresistcomposition comprising the step of passing a photoresist compositioncontaining a resin component (A), an acid-generating component (B) forgenerating an acid under exposure, and an organic solvent (C) through afirst filter equipped with a first membrane having a pore diameter of0.04 μm or less and made of a NYLON membrane. Also, the third embodimentprovides a filtering device comprising: a storing part for storing aphotoresist composition containing a resin component (A), anacid-generating component (B) for generating an acid under exposure, andan organic solvent (C); and a first filtering part for passing thephotoresist composition through, wherein the first filtering part has afirst filter equipped with a first membrane made of a NYLON membrane of0.04 μm or less.

The third embodiment is different from the first embodiment in that thefirst filtering part 2 shown in FIG. 1 is equipped with the first filter2 a having the NYLON membrane having the pore diameter of 0.04 μm orless.

Examples of the filters having membrane include the above ULTIPLEAT(registered trademark), P-NYLON FILTER (product name, manufactured byJapan Pall Corporation, zeta potential of about −12 to 16 mV, porediameter of 0.04 μm, 77 dyne/cm) made of NYLON 66 (registeredtrademark).

Since the first filter equipped with the first membrane composed by theNYLON membrane having the pore diameter of 0.04 μm or less is used inthe third embodiment, as described in the second embodiment, generalNYLON 66 (Material) with which the filter is not equipped is notcontained in the NYLON membrane of the filter. Therefore, NYLON 66(Material) which is not equipped in the filter having the criticalsurface tension of 46 dyne/cm does not correspond to the NYLON membraneof the filter.

The pore diameter of the membrane used for the first filter 2 a is thenominal value of the manufacturer of the filter. In the wholeembodiments shown herein, particularly in this embodiment, it is notsimply said that the smaller the pore diameter is, the defect reductioneffect and the effect of the storage stability characteristic as aresist solution are improved. It is preferable to select the porediameter in consideration of the relationship between the size and themembrane material.

For example, even when filtration by only the first filter 2 a isperformed without using the second filter 4 a, or even when the firstfilter 2 a is combined with the second filter 4 a to filter, a productis used, in which the pore diameter of the membrane of the first filter2 a is 0.04 μm or less. If the pore diameter becomes too small, theproductivity (the manufacture of the resist composition and thethroughput of coating) tends to be reduced. Although the lower limit isabout 0.01 μm, the lower limit is most practically set to 0.02 μm ormore. The effect of the reduction of defects, particularly minute scum,microbridges and improvement of storage stability as a resist solutionis acheived by the lower limit of 0.04 μm or less. The effect due to thenumerical limit is exhibited by the combination with the fact that themembrane is made of NYLON as described above.

A preferable aspect in the case of combining the filtration using thesecond filter 4 a is the same as that of the first embodiment.

In the third embodiment, a membrane which satisfies the aboverequirements and is not subjected to charge modification is preferable.The charge modification is the same as described in the secondembodiment. That is, the membrane has zeta potential of more than −20 mVbut no more than 15 mV; preferably more than −20 mV but no more than 10mV; more preferably more than −20 mV but less than 10 mV; particularlypreferably negative zeta potential (more than −20 mV). Thereby, thephotoresist composition is preferably obtained in which the sensitivityand the size of the resist pattern after being filtrated aresubstantially unchanged even if the photoresist composition itself isfiltrated. The negative zeta potential is −5 mV or less (more than −20mV), preferably −10 to −18 mV, and more preferably −12 to −16 mV.

The reduction of defects, particularly the effect of the reduction ofminute scum, microbridges and improvement of the storage stability as aresist solution is acheived by using the first filter equipped with thefirst membrane composed of the NYLON membrane having the pore diameterof 0.04 μm or less.

Although the reason is not clear, the present inventors speculate thatthe cause of the defects and foreign matter, particularly the resin withhigh contents of units having a polar group such as a lactone group or ahydroxyl group such as construction units (a2) and (a3) described belowcan be selectively absorbed into the surface of the membrane by theNYLON membrane by its specific pore diameter, whereby the filtrationefficacy is improved.

[Photoresist Composition Suitable for Applying the Present Invention]

The present invention is suitable for manufacture of a chemicallyamplified photoresist composition essentially containing a resincomponent (A) and an acid-generating agent (B). That is, the method formanufacturing the present invention is suitable for treating thephotoresist composition containing the components, and the filteringdevice and coating device of the present invention are suitable fortreating the photoresist composition containing the components.

The above component (A) is not particularly limited as long as thecomponent (A) is used for the chemically amplified photoresistcomposition. Examples thereof include a resin containing a constructionunit derived from (meta)acrylate ester suitably used as the resincomponents of the photoresist composition for the ArF excimer laser.

As described above, when ArF excimer laser on wards as the light source,namely, ArF excimer lasers, F₂ excimer lasers, EUV, EB or the like areparticularly used, minute scum and microbridges after development whichdo not pose large problems in the resist for the KrF excimer laser poseproblems. Thereby, the present invention is preferably applied to theresist for the light source and the process and device using the lightsource.

-Component (A)

As the component (A), an alkali soluble resin or a resin which canbecome alkali soluble is usually used. The former is a negative typephotoresist composition, and the latter is a positive type photoresistcomposition.

The component (B) and a crosslinking agent are blended with the negativetype photoresist composition. When an acid is generated by the component(B) due to exposure at the time of forming the resist pattern, this acidacts on the crosslinking agent, and the above component (A) iscross-linked. Thereby, the photoresist composition becomes alkaliinsoluble. As the crosslinking agent, for example, an amino crosslinkingagent such as melamine having a methylol group or an alkoxy methylgroup, urea or glycoluryl is usually used.

The positive type component (A) has an acid-dissociable dissolutioninhibiting group and is alkali insoluble. When the acid is generated bythe component (B) due to exposure, the acid-dissociating insolubleinhibiting group is dissociated by the acid, and thereby the abovecomponent (A) becomes alkali soluble.

Particularly, when the present invention is applied to the manufactureof a photoresist composition (particularly positive type) using a resinhaving a construction unit derived from (meta)acrylate ester, it ispreferable that the foreign matter causing the defects and degradationof storage stability characteristic as a resist solution are effectivelyremoved by the first filter. It is preferable that a resin having aconstruction unit derived from (meta)acrylate ester is 15 mol % or more.Although the upper limit is not particularly limited, the upper limitmay be 100 mol %.

Although the reason is not clear, the present inventors consider thatthe resin tends to contain a monomer or oligomer or the like having theproperty removed by the first filter which causes the defects, theforeign matter or the increase of the foreign matter with the lapse oftime.

Specifically, for example, the resin is preferably used for manufactureof the positive type photoresist composition using the resin containingthe following construction unit (a1).

-   (a1): a construction unit derived from (meta)acrylate ester having    an acid-dissociable dissolution inhibiting group. The resin may    contain the following construction units-   (a2) and (a3) arbitrarily, preferably the construction units (a1)    and (a2), and more preferably construction units (a1), (a2) and    (a3).-   (a2): a construction unit derived from (meta)acrylate ester having a    lactone ring. (a3): a construction unit derived from (meta)acrylate    ester having a hydroxyl group and/or a cyano group.

Particularly, the positive type photoresist compositions for the ArFexcimer laser on wards containing the above construction units (a1) and(a2) are mainly used. It is thought that various monomers, oligomers andother by-product materials cause defects or foreign matter with thelapse of time or the like in polymers obtained by polymerizing monomershaving such a different polarity. The above unit (a1) has a smallpolarity (hydrophobicity is large), and the polarity of the above unit(a2) tends to be large.

However, the storage stability characteristic as a resist solution canbe improved and the occurrence of defects can be reduced in thephotoresist composition using the resin obtained by combining andpolymerizing the monomers having a different polarity by applying theabove first embodiment, second embodiment or third embodiment of thepresent invention. Particularly, since defects such as minute scum andmicrobridges tend to pose problems in the positive type photoresistcomposition for the ArF excimer laser on wards, the present invention iseffectively applied therefor.

A copolymer having the construction units (a1) to (a3) or theconstruction units (a1) to (a4) described below is processed by thepresent invention. Thereby, the present inventors confirmed that a resinwith high content of units having a polar group such as the constructionunits (a2) and (a3) is selectively trapped in the filter (particularly,one having negative zeta potential) equipped with the first membrane,and the resin is removed from the resist composition.

This resin can be synthesized by the conventional method.

-Construction Unit (a1)

In the construction unit (a1), an acid dissociable dissolutioninhibiting group is not particularly limited. Typically, an aciddissociable dissolution inhibiting group forming a cyclic or lineartertiary alkyl ester with a carboxyl group of (meta)acrylic acid iswidely known. Of these, examples include an aliphatic monocyclic or analiphatic polycyclic group containing an acid-dissociating dissolutioninhibiting group. An aliphatic polycyclic group containing an aciddissociable dissolution inhibiting group is preferably used, whichparticularly excels in dry etching resistance in view of formation ofthe resist pattern.

Examples of the monocyclic groups include a group obtained by excludingone hydrogen atom from cyclo alkane or the like.

Examples of the aliphatic polycyclic groups include a group obtained byexcluding one hydrogen atom from bicyclo alkane, tricyclo alkane,tetracyclo alkane or the like.

Specific examples include a group obtained by excluding one hydrogenatom from polycycloalkane such as cyclohexane, adamantane, norbornane,isobornane, tricyclodecane or tetracyclododecane. For example, thealiphatic polycyclic group can be selectively used from the large numberof aliphatic polycyclic groups proposed, in the resin component for theresist composition for the ArF excimer laser.

Of these, the adamantyl group, the norbornyl group and thetetracyclododecanyl group are industrially preferable.

More specifically, it is preferable that the construction unit (a1) isat least one selected from the following general formulae (I), (II) and(III),

wherein R is a hydrogen atom or a methyl group, and R¹ is a lower alkylgroup,

wherin R is a hydrogen atom or a methyl group, and R² and R³ areindependently a lower alkyl group,

wherein R is a hydrogen atom or a methyl group, and R⁴ is a tertiaryalkyl group.

In the above formulae, R¹ is preferably a lower alkyl group having 1 to5 carbon atoms and being linear or branched. Examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, an-butyl group, an isobutyl group, a pentyl group, an isopentyl group anda neopentyl group. Of these, the alkyl group having carbon atoms of 2 ormore, preferably having 2 to 5 carbon atoms is preferable. In this case,the alkyl group tends to have higher acid-dissociability than the methylgroup. The methyl group and the ethyl group are industrially preferable.

It is preferable that R² and R³ are independently lower alkyl groupshaving 1 to 5 carbon atoms respectively. Such a group tends to havehigher acid-dissociability than the 2-methyl-2-adamantyl group.

More specifically, it is preferable that R² and R³ are independentlylinear or branched lower alkyl group being as the above R¹. Of these, itis industrially preferable that both R² and R³ are methyl groups, andspecific examples include a construction unit derived from2-(1-adamantyl)-2-propyl (meta)acrylate.

R⁴ is a tertiary alkyl group such as a tert-butyl group or a tert-amylgroup, and the tert-butyl group is industrially preferable.

A group —COOR⁴ may be combined with the third or fourth position of thetetracyclo dodecanyl group shown in the formula. However, since themetamers are mixed, the connected position cannot be specified. Althoughthe carboxyl group residue of a (meta) acrylate construction unit isalso combined with the eighth or nineth position shown in the formulasimilarly, the connection position cannot be specified.

The construction unit (a1) is preferably one represented by the abovegeneral formula (I) or (II), and particularly preferably one representedby the above general formula (I).

The amount of the construction unit (a1) is 20 to 60 mol % relative tothe sum total of all of the construction unit of the component (A), andpreferably 30 to 50mol %.

-Construction Unit (a2)

Examples of the construction unit (a2) include a construction unit inwhich a monocyclic group made of a lactone ring or an aliphaticpolycyclic group having the lactone ring is combined with an ester sidechain part of a (meta)acrylate ester. At this time, the lactone ringshows one ring containing an —O—C(O)— structure, and this is counted asthe first ring. Therefore, herein, that including only the lactone ringis referred to as a monocyclic group, and that further including otherring structure is referred to as an aliphatic polycyclic groupregardless of the structure.

Specific examples of the construction unit (a2) include a monocyclicgroup obtained by excluding one hydrogen atom from gamma-butyrolactone,and an aliphatic polycyclic group obtained by excluding one hydrogenatom from a lactone ring-containing polycycloalkane.

Specifically, for example, construction units represented by thefollowing structural formulae (IV) to (VII) are preferable,

wherein R is a hydrogen atom or a methyl group, and m is 0 or 1.

wherein R is a hydrogen atom or a methyl group.

wherein R is a hydrogen atom or a methyl group.

wherein R is a hydrogen atom or a methyl group.

The amount of the construction unit (a2) is 20 to 60 mol % relative tothe sum total of all of the construction units of the component (A), andpreferably 20 to 50 mol %.

-Construction Unit (a3)

The construction unit (a3) can be suitably and selectively used from thelarge number of proposed aliphatic polycyclic groups, for example, inthe resin for the photoresist composition for the ArF excimer laser. Forexample, it is preferable that the construction unit (a3) contains ahydroxyl group and/or a cyano group-containing aliphatic polycyclicgroup. It is more preferable that the construction unit (a3) contains ahydroxyl group or the cyano group-containing aliphatic polycyclic group.

The aliphatic polycyclic group can be suitably selected and used fromthe same large number of aliphatic polycyclic groups as thoseillustrated in the explanation of the construction unit (a1).

Specifically, the construction unit (a3) having a hydroxylgroup-containing an adamantyl group, a cyano group-containing adamantylgroup or a carboxyl group-containing tetracyclododecanyl group ispreferably used.

More specific examples include the construction unit represented by thefollowing general formula (VIII),

wherein R is a hydrogen atom or a methyl group.

The amount of the construction unit (a3) is 10 to 50 mol % relative tothe sum total of all of the construction units of the component (A), andpreferably 20 to 40 mol %.

The component (A) may include another construction unit (a4) other thanconstruction units (a1) to (a3).

The construction unit (a4) is not particularly limited as long as theconstruction unit (a4) is another construction unit which is notclassified with the above construction units (a1) to (a3).

For example, a construction unit or the like containing an aliphaticpolycyclic group and derived from (meta)acrylate ester is preferable.

For example, those illustrated in the case of the above constructionunit (a1) can be illustrated as the aliphatic polycyclic group, or thelike, and a large number of aliphatic polycyclic groups conventionallyknown as those used for the resin component of the photoresistcomposition for the ArF excimer laser, for the KrF positive excimerlaser (preferably, for the ArF excimer laser) or the like can be used.

Particularly, it is preferable that the aliphatic polycyclic group beingat least one or more selected from a tricyclodecanyl group, an adamantylgroup and a tetracyclododecanyl group is industrially and easilyobtained.

Specific examples of the construction units (a4) include the structuresof following (IX) to (XI),

wherein R is a hydrogen atom or a methyl group,

wherein R is a hydrogen atom or a methyl group,

wherein R is a hydrogen atom or a methyl group.

The amount of the construction unit (a4) is preferably 1 to 25 mol %relative to the sum total of all of the construction units of thecomponent (A), and more preferably 10 to 20 mol %.

Although the mass-average molecular weight (polystyrene equivalent,weight average molecular weight determined by gel permeationchromatography) of the resin of the component (A) is not particularlylimited, the mass-average molecular weight is preferably 5000 to 30000,more preferably 8000 to 20000.

The component (A) can be constituted by a resin of one or more kinds,for example, a resin of one or more kinds having the unit derived fromthe above (meta) acrylic of one or more kinds may be used, and further aresin of another kind can also be mixed and used.

-Component (B)

Any conventionally known acid-generating agent in the chemicallyamplified resist can be suitably selected and used as the component (B).

Examples include onium salts such as diphenyl iodoniumtrifluoromethanesulfonate, (4-methoxyphenyl)phenyl iodoniumtrifluoromethanesulfonate, bis(p-tert-butylphenyl)iodoniumtrifluoromethanesulfonate, triphenyl sulfoniumtrifluoromethanesulfonate, (4-methoxyphenyl)diphenyl sulfoniumtrifluoromethanesulfonate, (4-methylphenyl)diphenyl sulfoniumnonafluorobutanesulfonate, (p-tert-butylphenyl)diphenyl sulfoniumtrifluoromethanesulfonate, diphenyl iodonium nonafluorobutanesulfonate,bis(p-tert-butylphenyl)iodonium nonafluorobutanesulfonate, and triphenylsulfonium nonafluorobutanesulfonate. Of these, an onium salt whichcontains a fluoroalkylsulfonate ion as an anion is preferable.

The component (B) may be used singly or in combination of two or morekinds. For example, the blended amount is set to 0.5 to 30 parts by massrelative to 100 parts by mass of the component (A).

-Component (C)

The component (C) is an organic solvent.

The component (C) may be used, which can dissolve the above component(A) and the above component (B) to produce a uniform solution. One ormore kinds can be arbitrarily and suitably selected and used fromconventionally known chemically amplified resists.

Specific examples of the component (C) include gamma-butyrolactone;ketones such as acetone, methyl ethyl ketone, cyclohexanone, methylisoamyl ketone and 2-heptanone; polyhydric alcohols and derivativesthereof such as ethylene glycol, ethylene glycolmonoacetate, diethyleneglycol, diethylene glycolmonoacetate, propylene glycol, propylene glycolmonoacetate, dipropylene glycol or a mono-methyl ether, monoethyl ether,monopropyl ether, monobutyl ether or monophenyl ether of dipropyleneglycol monoacetate; cyclic ethers such as dioxane; and esters such asmethyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butylacetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate andethyl ethoxypropionate. These organic solvents may be used singly or incombination of two or more kinds.

Of these, propyleneglycolmonomethyletheracetate (PGMEA) and ethyllactate (EL) or the like are preferable. Gamma-butyrolactone may beincluded in the component (C) by from about 5 to about 20% by mass.

The concentration of the component (C) is set so that the photoresistcomposition can be applied suitably to the substrate or the like.

-Other Components

Other components can be further blended with the photoresist compositionif desired.

For example, so as to improve the shape of the resist pattern and postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer or the like, a nitrogen-containing organiccompound, for example, known amines, preferably a secondary loweraliphatic amine and a tertiary lower aliphatic amine can be contained asa component (D).

Herein, the lower aliphatic amine means an amine of alkyl or alkylalcohol having carbon atoms of 5 or less. Examples of the second andtertiary amines include trimethylamine, diethyl amine, triethyl amine,di-n-propyl amine, tri-n-propyl amine, tripentyl amine, diethanolamine,triethanolamine. Tertiary alkanolamine such as triethanolamine isparticularly preferable.

These may be used singly or in combination of two or more kinds.

The component (D) is usually used in the range of 0.01 to 5.0 parts bymass relative to 100 parts by mass of the component (A).

So as to prevent sensitivity degradation due to the addition of theabove component (D) and improve the post exposure stability of thelatent image formed by the pattern-wise exposure of the resist layer orthe like, the organic carboxylic acid, or the oxo acid of phosphor orits derivative can be further contained as a component (E). Thecomponent (D) and the component (E) can also be used together, and anyone kind thereof can also be used.

Preferable examples of the organic carboxylic acids include malonicacid, citric acid, malic acid, succinic acid, benzoic acid and salicylicacid.

Examples of the oxo acid of phosphor or its derivative includephosphoric acid or derivatives such as esters thereof, such asphosphoric acid, di-n-butyl phosphate and diphenyl phosphate; phosphonicacid and derivatives such as ester thereof, such as phosphonic acid,dimethyl phosphonate, di-n-buthyl phosphonate, phenylphosphonic acid,diphenyl phosphonate and dibenzyl phosphonate; and phosphinic acid andderivatives thereof such as esters thereof, such as phosphinic acid andphenyl phosphinate. Of these, the phosphonic acid is particularlypreferable.

0.01 to 5.0 parts by mass of component (E) is used per 100 parts by massof the component (A).

The photoresist composition can further contain an additive agent havingmiscibility therewith if desired, for example, an additional resin forimproving the performance of the resist membrane, a surface-active agentfor improving coating property, a dissolution depressant, a plasticizer,a stabilizer, a colorant or a halation prevention agent or the like.

The resist pattern using the photoresist composition can be formed bythe conventional method.

For example, the above photoresist composition is first coated onto asubstrate such as a silicon wafer by a spinner or the like. Thephotoresist composition is prebaked (PAB processing) for 40 to 120seconds, preferably for 60 to 90 seconds at 80 to 150° C. KrF, ArF, orF₂ excimer-laser light, Extreme UV (extreme ultraviolet radiation), anEB (electron beam) or X-ray or the like is selectively radiated, forexample, by an exposure device or the like through the desired maskpattern or drawn. PEB (post exposure baking) processing is thenperformed at 80 to 150° C. for 40 to 120 seconds, preferably for 60 to90 seconds. This is then developed by using an alkali developingsolution, for example, tetramethyl ammonium hydroxide aqueous solutionof 0.1 to 10% by mass. Thus, a resist pattern faithful to the maskpattern can be achieved.

An organic or inorganic antireflection membrane can also be providedbetween the substrate and the coating layer of the resist composition.

EXAMPLES

Hereinafter, the present invention will be described in detail based onthe Examples.

[Evaluation Method]

Various properties of the photoresist compositions of the Examples orComparative Examples to be described below were obtained as follows.

(1) Storage Stability Characteristic of a Resist Solution

In (Example 1-1) to (Comparative Example 1-2), the storage stabilitycharacteristic as a resist solution of the photoresist composition afterstoring at 40° C. after manufacture (six months, one month, or twoweeks) was evaluated by using a liquid particle counter (manufactured byRion Company, product name: KS-41).

The measuring limit was 20000 pieces/cm³ or more.

The amount of foreign matter in the photoresist composition immediatelyafter manufacture was adjusted to 10 pieces/cm³ or less in terms ofparticles of 0.3 μm or more.

In (Example 2-1) to (Comparative Example 2-3), the storage stabilitycharacteristic as a resist solution of the photoresist composition afterstoring at room temperature after manufacture (one month) was evaluatedusing a liquid particle counter (manufactured by Rion Company, productname: KS-41).

The measuring limit was 20000 pieces/cm³ or more.

The amount of the foreign matter in the photoresist compositionimmediately after manufacture was adjusted to 900 pieces/cm³ or less interms of particles of 0.15 μm or more.

(2) Defects

The adjusted photoresist composition (positive type) was applied on asilicon wafer (diameter of 200 mm) by using a spinner. The photoresistcomposition was prebaked at 130° C. for 90 seconds on a hot plate (PABprocessing), and dried to form a resist layer having a membranethickness of 350 nm.

Then, the resist layer was selectively irradiated with the ArF excimerlaser (193 nm) via a mask pattern by an ArF exposure device NSR-S302 (NA(numerical aperture)=0.60, sigma=0.75, manufactured by NikonCorporation).

The PEB processing was performed at 120° C. for 90 seconds, and puddledevelopment was then performed at 23° C. for 60 seconds by a tetramethylammonium hydroxide aqueous solution of 2.38% by mass. The resist layerwas then washed with water for 20 seconds, and dried to form aline-and-space pattern of 250 nm (Example 1-2 to Comparative Example1-2). In Example 2-1 to Comparative Example 2-3, a line-and-spacepattern of 130 nm was formed.

The defects were measured by a surface defect observation apparatus(KLA2132; product name), manufactured by KLA Tencor Company, and thenumber of defects in the wafer were evaluated. Three wafers wererespectively used for the tests in the Example and Comparative Example,and the average value thereof was calculated.

In all Examples and Comparative Examples, a measuring SEM (S-9220,manufactured by Hitachi, Ltd.) confirmed that the defects were aso-called bridge type in which a bridge state was formed between linepatterns.

Example 1-1

The following components (A) to (D) were mixed and dissolved tomanufacture a positive type photoresist composition (for the ArF excimerlaser).

-   Component (A): a copolymer of 100 parts by mass (mass-average    molecular weight of 10000, dispersity of 1.6) obtained by    copolymerizing the following monomers: 2-methyl-2-adamantyl    methacrylate of 40 mol % (equivalent to the construction unit (a1));    alpha-gamma-butyrolactone methacrylate of 40 mol % (equivalent to    the construction unit (a2)); and 3-hydroxy-1-adamantyl methacrylate    of 20 mol % (equivalent to the construction unit (a3))-   Component (B): triphenyl sulfonium nonafluorobutanesulfonate of 2.0    parts by mass-   Component (C): a mixed solvent of 750 parts by mass (mass ratio of    6:4) of PGMEA and EL-   Component (D): triethanol amine of 0.2 parts by mass

A photoresist composition of 4000 ml was supplied to the first filteringpart equipped with the following first filter, and the second filteringpart equipped with the second filter from the storing part, and wassequentially filtered to obtain the photoresist composition. Thefiltration pressure of the photoresist composition supplied to the firstfiltering part and the second filtering part was set to 0.4 kgf/cm².

The first filter: made of NYLON, ULTIPORE N66 (product name:manufactured by Japan Pall Corporation)

The zeta potential of the first filter was −15 mV, and the pore diameterwas 0.04 μm. For the specification, the filtration pressure[withstanding differential pressure (38° C.)] was 4.2 kgf/cm², and thesurface area (filtration area) was 0.09 m². The filter was a disposabletype, and had a diameter of 72 mm and a height of 114.5 mm. The criticalsurface tension was 77 dyne/cm. The second filter: made of polypropylene(product name: UNIPORE POLYFIX, manufactured by Kitz Corporation)

The pore diameter of the second filter was 0.02 μm. For thespecification, the filtration pressure [withstanding differentialpressure (20° C.)] was 0.4 MPa, and the surface area (filtration area)was 3400 cm². The filter was a disposable type, and had a diameter of 58mm and a height of 148.6 mm. The critical surface tension was 29dyne/cm.

The storage stability characteristic as a resist solution of thephotoresist composition after storing at 40° C. for six months wasalmost unchanged as compared with that immediately after manufacture.

The average number of defects was 10 pieces or less per one wafer.

Substances adsorbed into the first filter were analyzed. The molar ratioof the above alpha-gamma-butyrolactone methacrylate unit and the above3-hydroxy-1-adamantyl methacrylate unit among the above (a1) to (a3) wasfound to be more than the molar ratio of the original copolymer in thephotoresist composition and to be an insoluble resin.

Example 1-2

The storage stability characteristic as a resist solution and thedefects were evaluated in the same manner as in Example 1-1 by using thesame filters, except that the first filter was changed to a filter of anULTIPORE N66 (product name: manufactured by Pall Corporation) made ofNYLON having pores with the pore diameter of 0.02 μm. The filtrationpressure was adjusted according to the filter.

As a result, the storage stability characteristic after one month at 40°C. was almost unchanged as compared with that immediately aftermanufacture.

The average number of defects was 10 pieces or less per one wafer.

Example 1-3

The storage stability characteristic as a resist solution and thedefects were evaluated in the same manner as in Example 1-1 by using thesame first filter, and a second filter which was the same as that ofExample 1-1 except that it was a filter (product name: MACRO GUARD UPEfilter, manufactured by Mykrolis Corporation) having the same porediameter as that of the second filter of Example 1-1 and made ofpolyethylene. The filtration pressure was adjusted according to thefilter. The critical surface tension of the membrane of the secondfilter was 31 dyne/cm. As a result, the storage stability characteristicafter one month at 40° C. was almost unchanged as compared with thatimmediately after manufacture. The average number of defects was 10pieces or less per one wafer.

Example 1-4

The storage stability characteristic as a resist solution and thedefects were evaluated in the same manner as in Example 1-1 by using thesame first filter, except that the second filter was not used.

As a result, the storage stability characteristic as a resist solutionafter one month at 40° C. was almost unchanged as compared with thatimmediately after manufacture. The average number of defects was 10pieces or less per one wafer. However, when the defects were similarlymeasured after one month at 40° C., the average number of defects was 20to 30 pieces per one wafer.

Comparative Example 1-1

The photoresist composition was prepared in the same manner as inExample 1-1, except that the first filter was changed to the followingfilter, and the storage stability characteristic as a resist solutionand the defects were evaluated. The first filter: made ofpolytetrafluoroethylene (product name: ENFLON, manufactured by PallCorporation).

The zeta potential of the first filter was −20 mV, and the pore diameterwas 0.05 μm. Referring to the specification, the filtration pressure[withstanding differential pressure (38° C.)] was 3.5 kgf/cm², and thesurface area (filtration area) was 0.13 m². The critical surface tensionwas 28 dyne/cm. The filter was a disposable type, and had a diameter of72 mm and a height of 114.5 mm.

As a result, the storage stability characteristic as a resist solutionafter two weeks at 40° C. exceeded the measuring limit, and was not ableto be measured.

The average number of defects was 5000 pieces per one wafer.

The measuring SEM confirmed that the defects were a so-called bridgetype in which a bridge state was formed between line patterns.

Comparative Example 1-2

The storage stability characteristic as a resist solution was evaluatedin the same manner as in Example 1-1, except that a filter of N66POSIDDYNE (product name: manufactured by Pall Corporation, zetapotential of 18 mV) made of NYLON having pores with the pore diameter of0.1 μm was used as the first filter in Example 1-1. The filtrationpressure was adjusted according to the filter.

As a result, the storage stability characteristic as a resist solutionafter two weeks at 40° C. exceeded the measuring limit, and was not ableto be measured. It was unnecessary to measure the defects.

Example 2-1

The following components (A) to (D) were mixed and dissolved tomanufacture a positive type photoresist composition (for an ArF excimerlaser).

-   Component (A): a copolymer of 100 parts by mass (mass-average    molecular weight of 11000, dispersity of 2.5) obtained by    copolymerizing the following monomers:-   2-methyl-2-adamantyl methacrylate of 35 mol % (equivalent to the    construction unit (a1): both R and R¹ are a methyl group in general    formula (I));-   alpha-gamma-butyrolactone methacrylate of 35 mol % (equivalent to    the construction unit (a2): R is a methyl group in general formula    (VII));-   3-hydroxy-1-adamantyl methacrylate of 15 mol % (equivalent to the    construction unit (a3): R is a methyl group in general formula    (VIII)); and-   tricyclodecanyl methacrylate of 15 mol % (equivalent to the    construction unit (a4): R is a methyl group in general formula    (IX)).-   Component (B): triphenyl sulfonium nonafluorobutanesulfonate of 2.0    parts by mass-   Component (C): PGMEA of 733 parts by mass (adjusted so that the    solid content concentration in the composition is set to 12% by    mass)-   Component (D): triethanol amine of 0.2 part by mass

The photoresist composition of 4000 ml was passed through the filtermade of polytetrafluoroethylene used in Comparative Example 1-1, andpre-filtration for passing the photoresist composition through throughthe same second filter as that of Example 1-1 was then performed.

The photoresist composition was then passed through an ULTIPLEAT(registered trademark: ULTIPLEAT) P-NYLON Filter (product name:manufactured by Japan Pall Corporation, zeta potential of about −12 to−16 mV, pore diameter of 0.04 μm, and critical surface tension of 77dyne/cm) made of NYLON 66 (registered trademark) as the first filter.

The photoresist composition was evaluated.

The number of defects was 14 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.15 μm ormore was 982 pieces.

Substances adsorbed into the first filter were analyzed. The molar ratioof the above alpha-gamma-butyrolactone methacrylate unit and the above3-hydroxy-1-adamantyl methacrylate unit among the above quaternary units[(a1) to (a4)] was found to be more than the molar ratio of the originalcopolymer in the photoresist composition and to be an insoluble resinhaving a mass-average molecular weight of about 40000.

Comparative Example 2-1

The photoresist composition the same as Example 2-1 was passed throughthe filter made of polytetrafluoroethylene used in Comparative Example1-1 after the same pre-filtration as that of Example 2-1 to prepare thephotoresist composition. The photoresist composition was evaluated inthe same manner as in Example 2-1.

The number of defects was 4100 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.15 μm ormore was 6509 pieces.

Comparative Example 2-2

The photoresist composition the same as Example 2-1 was passed throughthe same pre-filtration as that of Example 2-1, thereafter, it waspassed through the filter which was the same as the second filter usedin Example 1-1 and was made of polypropylene to prepare the photoresistcomposition. The photoresist composition was evaluated in the samemanner as in Example 2-1.

The number of defects was 34 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.15 μm ormore was 1070 pieces.

Comparative Example 2-3

A positive type photoresist composition was prepared and evaluated inthe same manner as in Comparative Example 2-2, except that the porediameter of the filter used in Comparative Example 2-2 afterpre-filtration and made of polypropylene was changed to 0.05 μm from0.02 μm. The critical surface tension was the same as that used inComparative Example 2-2.

The number of defects was 244 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.15 μm ormore was 1030 pieces.

Comparative Example 2-4

The photoresist composition the same as Example 2-1 was passed throughthe same pre-filtration as that of Example 2-1, thereafter, it waspassed through a filter (product name: MACRO GUARD UPE filter,manufactured by Mykrolis Corporation) which was the same as the secondfilter used in Example 1-1 except that it was made of polyethylene, andthe pore diameter thereof was changed to 0.05 μm and thereby thephotoresist composition was prepared. The photoresist composition wasevaluated in the same manner as in Example 2-1.

The number of defects was 897 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.15 μm ormore was 1819 pieces.

Example 3-1

The same composition as the positive type photoresist composition ofExample 2-1 was manufactured, except that salicylic acid of 0.2 parts bymass as the component (E) was added to the positive type photoresistcomposition of Example 2-1. The photoresist composition was then passedthrough the pre-filtration and the first filter in the same manner as inExample 2-1.

The photoresist composition was evaluated.

The number of defects was about 20 pieces.

Referring to the storage stability as a resist solution after storingfor one month, the number of particles having a diameter of 0.20 μm ormore was 7 pieces or less.

The photoresist composition was applied on a silicon wafer (diameter of200 mm) using a spinner. The photoresist composition was prebaked on ahot plate at 130° C. for 90 seconds (PAB processing), and dried to forma resist layer having a membrane thickness of 400 nm.

Then, the resist layer was selectively irradiated with the ArF excimerlaser (193 nm) via a mask pattern by an ArF exposure device NSR-S302 (NA(numerical aperture)=0.60, sigma=0.75, manufactured by NikonCorporation).

The PEB processing was performed at 120° C. for 90 seconds, and puddledevelopment was then performed at 23° C. for 60 seconds by a tetramethylammonium hydroxide aqueous solution of 2.38% by mass. The resist layerwas then washed with water for 20 seconds, and dried to form a resistpattern.

The resist pattern size before filtering by using the first filter wascompared with that after filtering, and the pattern size of 160 nm wasnot largely changed.

Comparative Example 3-1

The storage stability characteristic as a resist solution was evaluatedin the same manner as in Example 3-1, except that a filter of N66POSIDDYNE (product name: manufactured by Pall Corporation, zetapotential of 18 mV, critical surface tension of 77 dyne/cm) used inComparative Example 1-2 and made of NYLON with pores having a porediameter of 0.1 μm was used as the first filter in Example 3-1.

As a result, the storage stability characteristic as a resist solutionafter two weeks at 40° C. exceeded the measuring limit, and was not ableto be measured.

It was unnecessary to measure the defects.

The resist pattern size obtained by using a resist composition afterfiltering by using the first filter of Comparative Example 3-1 wascompared with that obtained by using a resist composition beforefiltering, and the pattern size of 160 nm was changed by about 15 nm.

Example 4-1

FIG. 2 shows the structure of the coating device of a photoresistcomposition equipped with the filtering device used in Example 4-1.

In Example 4-1, the positive type photoresist composition of Example 2-1was used.

Hereinafter, the device will be described according to the operatingprocedure.

A photoresist composition 7 is drawn from a reservoir tank 10 by a pump11, and is passed through an introducing pipe 9 and a first filteringpart 12. The resulting photoresist composition is supplied to asubstrate 14 such as a silicon wafer from a nozzle 13 of a coatingdevice. The composition is filtered by a first filter 12 a equipped witha first membrane and provided in the first filtering part 12.

The composition after being filtered is dropped from the nozzle 13. Inthat case, when a rotary shaft 17 in a coating part 18 of the coatingdevice is rotated, a supporting part 15 of the substrate 14 attached tothe tip of the rotary shaft 17 rotates the substrate 14 arrangedthereon. The photoresist composition dropped on the substrate 14 isspread by centrifugal force, and is applied on the substrate 14. Abottomed cylindrical body (defense wall) is provided around the nozzle13, the substrate 14 and the supporting part 15 so that these aresurrounded, and the rotary shaft 17 penetrates the bottom part. Thesubstrate is rotated by the bottomed cylindrical body 16 to prevent thephotoresist composition from scattering in all directions. A pipe 6 forpressurization is provided in a storing part 8. The photoresistcomposition 7 is pressurized to the reservoir tank 10 from the storingpart 8 by inactive gas such as nitrogen, and thereby the photoresistcomposition 7 can be supplied.

The reservoir tank 10 may be provided or may not be provided. The pump11 is not limited as long as the pump has a function for supplying thephotoresist from the storing part 8 to the coating part 18.

The second filtering part equipped with the second filter can beprovided at least one of before and after the first filtering part 12,and various modes for the combination of the filters can be selected asdescribed above for the filtering device.

Although the coating device showed an example of a spinner, variousmethods other than a spin coating such as a slit nozzle method have beenproposed in recent years for the coating methods, and devices have beenalso proposed. Thereby the coating device is not limited.

The coating device may be a coating-development device which can performa subsequent development process integratedly as described above. Forexample, “CLEAN TRACK ACT-8” or the like manufactured by Tokyo Electron,Ltd. could be used, and it was used in this Example.

The first filtering part 12 has the first filter equipped with the firstmembrane having zeta potential of more than −20 mV but no more than 15mV in distilled water of pH 7.0 in the third aspect, or the first filterequipped with the first membrane having the critical surface tension of70 dyne/cm or more in the fourth aspect, or the first filter equippedwith the first membrane composed by the NYLON membrane of 0.04 82 m orless in the eighth aspect. For example, P-NYLON or the like (productname: manufactured by Japan Pall Corporation, zeta potential of about−12 to −16 mV, pore diameter of 0.04 μm, critical surface tension of 77dyne/cm) equipped with a membrane made of NYLON 66 (registeredtrademark) can be used as the filter, and it was used in this example.

According to the device, the positive type resist layer is formed on thesubstrate 14 by the above series of treatments using the positive typephotoresist composition of Example 2-1. Afterward, in accordance withthe normal lithography process, the resist pattern is formed bypre-bake, selective exposure, PEB, development and rinse. The resistpattern after being formed is measured by using the surface defectobservation apparatus KLA2132 (product name) manufactured by KLA TencorCompany or the like, and the defects in the wafer are evaluated.

The second filter described in the first, second, third, fourth, seventhand eighth aspects may be used if needed.

In this Example, the lithography process was performed as follows.

The positive type photoresist composition of Example 2-1 was applied ona silicon wafer (diameter of 200 mm) using a spinner. The photoresistcomposition was prebaked on a hot plate at 130° C. for 90 seconds (PABprocessing), and dried to form a resist layer having a membranethickness of 350 nm.

Then, the resist layer was selectively irradiated with the ArF excimerlaser (193 nm) via a mask pattern by an ArF exposure device NSR-S302 (NA(numerical aperture)=0.60, sigma=0.75, manufactured by NikonCorporation).

The PEB processing was performed at 120° C. for 90 seconds, and puddledevelopment was then performed at 23° C. for 60 seconds by a tetramethylammonium hydroxide aqueous solution of 2.38% by mass. The resist layerwas then washed with water for 20 seconds, and dried to form aline-and-space pattern of 130 nm.

When the defects on the pattern were measured by the above KLA2132, thenumber thereof was 14 pieces, and the measurement showed very goodresults.

Comparative Example 4-1

The photoresist composition was prepared in the same manner as inExample 4-1, except that the first filter was changed to a filter(product name: ENFLON, manufactured by Pall Corporation) used inComparative Example 1-1 and made of polytetrafluoroethylene, and thedefects were evaluated.

As a result, when the defects on the pattern were measured, the numberthereof was 4100 pieces, and the measurement showed poor results.

Comparative Example 4-2

The photoresist composition was prepared in the same manner as inExample 4-1, except that the first filter was changed to a filter(product name: UNIPORE POLYFIX, manufactured by Kitz Corporation, porediameter of 0.02 μm) used as the second filter of Example 1-1 and madeof polypropylene, and the defects were evaluated.

As a result, when the defects on the pattern were measured, the numberthereof was 34 pieces, and the measurement showed poor results.

Comparative Example 4-3

The photoresist composition was prepared in the same manner as inExample 4-1, except that the first filter was changed to a filter madeof polypropylene which was the same as the filter used in ComparativeExample 2-3, and of which the pore diameter was 0.05 μm, and the defectswere evaluated.

As a result, when the defects on the pattern were measured, the numberthereof was 244 pieces, and the measurement showed poor results.

Comparative Example 4-4

The photoresist composition was prepared in the same manner as inExample 4-1, except that a filter made of polypropylene (product name:MACRO GUARD UPE filter, manufactured by Mykrolis Corporation) which wasmade of the same material as that of the second filter used in Example1-3 and was most widely equipped on the coating device and of which thepore diameter was 0.05 μm was used as the first filter, and the defectswere evaluated.

As a result, when the defects on the pattern were measured, the numberthereof was 897 pieces, and the measurement showed poor results.

From the results of the above Examples and Comparative Examples, it isclear that the storage stability characteristic as a resist solution wasremarkably improved by only changing the kind of membrane of the filterin the Examples according to the present invention.

The present inventors confirmed that minute scum and the microbridges atthe time of forming the resist pattern can be also reduced remarkably.The composition characteristics before and after filtration wereunchanged, and were good.

INDUSTRIAL APPLICABILITY

The present invention is effective for the method for manufacturing thephotoresist composition, the filtering device, the coating device andthe photoresist composition.

1. A method for manufacturing a photoresist composition comprising thestep of passing a photoresist composition containing a resin component(A), an acid-generating component (B) for generating an acid underexposure and an organic solvent (C) through a first filter equipped witha first membrane having at least one of the following characteristics:(i) having zeta potential of more than −20 mV but no more than 15 mV indistilled water of pH 7.0, (ii) having a critical surface tension of 70dyne/cm or more, or (iii) having a pore diameter of 0.04 μm or less andmade of a NYLON membrane.
 2. The method for manufacturing thephotoresist composition according to claim 1, wherein a filter equippedwith the first membrane having negative zeta potential in distilledwater of pH 7.0 is used as the first filter. 3-5. (canceled)
 6. Themethod for manufacturing the photoresist composition according to claim1, further comprising the step of passing the photoresist compositionthrough a second filter equipped with a second membrane made ofpolyethylene or polypropylene at least one of before and after the stepfor passing the photoresist composition through the first filter.
 7. Themethod for manufacturing the photoresist composition according to claim1, wherein the pore diameter of at least one of the first membrane andsecond membrane is 0.02 μm or more and 0.1 μm or less.
 8. The method formanufacturing the photoresist composition according to claim 1, whereinthe pore diameter of the first membrane is 0.02 μm or more and 0.04 μmor less.
 9. The method for manufacturing the photoresist compositionaccording to claim 8, wherein the pore diameter of the first membrane is0.04 μm.
 10. The method for manufacturing the photoresist compositionaccording to claim 1, wherein the component (A) is a resin having aconstruction unit derived from a (meta)acrylate ester.
 11. The methodfor manufacturing the photoresist composition according to claim 10,wherein the component (A) has a construction unit (a1) derived from a(meta)acrylate ester having an acid-dissociable dissolution inhibitinggroup, and a construction unit (a2) derived from a (meta)acrylate esterhaving a lactone ring.
 12. The method for manufacturing the photoresistcomposition according to claim 11, wherein the component (A) has aconstruction unit (a1) derived from a (meta)acrylate ester having anacid-dissociable dissolution inhibiting group, a construction unit (a2)derived from a (meta)acrylate ester having a lactone ring, and aconstruction unit (a3) derived from a (meta)acrylate ester having ahydroxyl group and/or a cyano group.
 13. The method for manufacturingthe photoresist composition according to claim 12, wherein the component(A) has a construction unit (a1) derived from a (meta)acrylate esterhaving an acid-dissociable dissolution inhibiting group, a constructionunit (a2) derived from a (meta)acrylate ester having a lactone ring, aconstruction unit (a3) derived from a (meta)acrylate ester having ahydroxyl group and/or a cyano group, and a construction unit (a4) whichis different from the construction units (a1) to (a3) and is derivedfrom an aliphatic polycyclic group-containing (meta)acrylate ester. 14.A filtering device comprising: a storing part for storing a photoresistcomposition containing a resin component (A), an acid-generatingcomponent (B) for generating an acid under exposure, and an organicsolvent (C); and a first filtering part for passing the photoresistcomposition through, wherein the first filtering part has a first filterequipped with a first membrane having at least one of the followingcharacteristics: (i) having zeta potential of more than −20 mV but nomore than 15 mV in distilled water of pH 7.0, (ii) having a criticalsurface tension of 70 dyne/cm or more or (iii) made of a NYLON membranehaving the pore diameter of 0.04 μm or less.
 15. The filtering deviceaccording to claim 14, wherein the first membrane has negative zetapotential in distilled water of pH 7.0. 16-18. (canceled)
 19. Thefiltering device according to claim 14, further comprising a secondfiltering part for passing the photoresist composition through a secondfilter equipped with a second membrane made of polyethylene orpolypropylene at least one of before and after the first filtering part.20. The filtering device according to claim 14, wherein the porediameter of at least one of the first membrane and second membrane is0.02 μm or more and 0.1 μm or less.
 21. The filtering device accordingto claim 14, wherein the pore diameter of the first membrane is 0.02 μmor more and 0.04 μm or less.
 22. The filtering device according to claim21, wherein the pore diameter of the first membrane is 0.04 μm.
 23. Thefiltering device according to claim 14, which is used for passing aphotoresist composition through, the photoresist composition includingthe component (A) having a construction unit derived from a(meta)acrylate ester.
 24. The filtering device according to claim 23,which is used for passing a photoresist composition through, thephotoresist composition including the component (A) containing aconstruction unit (a1) derived from a (meta)acrylate ester having anacid-dissociable dissolution inhibiting group, and a construction unit(a2) derived from a (meta)acrylate ester having a lactone ring.
 25. Thefiltering device according to claim 24, which is used for passing aphotoresist composition through, the photoresist composition includingthe component (A) having a construction unit (a1) derived from a(meta)acrylate ester having an acid-dissociable dissolution inhibitinggroup, a construction unit (a2) derived from a (meta)acrylate esterhaving a lactone ring, and a construction unit (a3) derived from a(meta)acrylate ester having a hydroxyl group and/or a cyano group. 26.The filtering device according to claim 25, which is used for passing aphotoresist composition through, the photoresist composition includingthe component (A) having a construction unit (a1) derived from a(meta)acrylate ester having an acid-dissociable dissolution inhibitinggroup, a construction unit (a2) derived from a (meta)acrylate esterhaving a lactone ring, a construction unit (a3) derived from a(meta)acrylate ester having a hydroxyl group and/or a cyano group, and aconstruction unit (a4) being different from the construction units (a1)to (a3) and derived from an aliphatic polycyclic group-containing(meta)acrylate ester.
 27. A coating device for a photoresist compositionequipped with filtering device according to claim
 14. 28. A photoresistcomposition obtainable by the method for manufacturing the photoresistcomposition according to claim
 1. 29-30. (canceled)
 31. A coating devicefor a photoresist composition equipped with the filtering deviceaccording to claim 1, wherein the first membrane is made of a NYLONmembrane having a pore diameter of 0.04 μm or less.